Starter nozzle for gas turbines



July 23, 1963 L. E. VARADI ET AL 3,

STARTER NOZZLE FOR GAS TURBINES Filed Nov. 29, 1960 2 Sheets-Sheet 1 IN V EN TOR.

[00/6 5. VIE/9.01 77/5000355 5M? 05 Wq/Q y July 23, 1963 L. E. VARADI ETAL STARTER NOZZLE FOR GAS 'IURBINES 2 Sheets-Sheet 2 Filed Nov. 29. 1960 T0125 1717/ E. Jauepm 1041756 P1554858 M /;G A I770 .041 y- INVEN United States Patent O 3,098,355 STARTER NOZZLE FOR GAS TURBINES Louis Ernest Varadi, Danvers, Theodore Edmond Bourque, Beverly, and Walter Pesarek, Swampscott, Mass, assignors to General Electric Company, a corporation of New York Filed Nov. 29, 1960, Ser. No. 72,470 1 Claim. (Cl. 60-3944) This invention relates to starter nozzles for gas turbines, and particularly to an improved fluid impingement starter nozzle construction.

The use of a fluid impingement starter nozzle for introducing a flow of starting fluid into a turbine requires that the fluid be conducted through the casing and into the working fluid flow path, and that it be directed to impinge at an appropriate angle upon the turbine buckets. It has been found expedient in the fulfillment of these requirements to extend nozzle-forming means at the desired angle through the casing and through the outer band of a nozzle diaphragm, for discharge between the partitions thereof. For example, it has been proposed to extend the contoured partitions of the nozzle diaphragm radially outwardly through the outer band, or alternatively to mount contoured stub vanes upon the interior of the casing to act as extensions of the partitions. The use of the partitions as guiding elements has been found desirable to provide a maximum effective nozzle length for optimum guidance of the starting fluid.

It is the primary object of our invention to provide an improved starting nozzle of simplified construction for guiding a flow of starting fluid to the partitions of a nozzle diaphragm.

It is a further object of our invention to provide an improved starting nozzle of simplified construction which may automatically be aligned with starting fluid ports in the turbine casing.

Further objects and advantages of the invention will become apparent as the following description of a preferred embodiment thereof proceeds.

Briefly stated, in accordance with a preferred embodi ment thereof, we may carry out our invention by providing a starting nozzle box comprising a group of planar partition plates circumferentially spaced about a nozzle diaphragm. An inner edge surface of each of the plates is secured to the outer edge of a corresponding nozzle partition, and the plate is inclined so that the edges defined by the parallel planar surfaces and the lower edge surface are parallel to lines tangent to trailing edge portions of the corresponding curved surface of the partition. The leading and trailing edge surfaces of the partition plates lie in parallel planes, and are enclosed by cover plates to form a series of nozzle passages of parallelogram crosssection between the partition plates.

The partition plates extend outwardly from the nozzle diaphragm through an outer band thereof, and abut upon an interior surface of the casing. The casing is formed with a plurality of circumferentially spaced ports arranged for alignment with the nozzle passageways, and a manifold extends arcuately about the casing to supply a flow of starting fluid through the nozzle box to the nozzle diaphragm and thence to the turbine. The nozzle diaphragm is segmented for mounting in split halves of the casing. Means are provided for locating the diaphragm segments in predetermined positions in the casing halves, and these means serve to automatically align the starter nozzle passageways with the casing ports upon assembly of the engine.

While the planar form of the partition plates does not ideally conform to the contoured surfaces of the nozzle diaphragm partitions, the improved nozzle box affords 3,098,355 Patented July 23, 1963 sufficiently accurate direction of the starting fluid into the diaphragm for starting purposes, and comprises a substantially simplified and easily-constructed device.

While the specification concludes with the claim particularly pointing out and distinctly claiming the subject matter which We regard as our invention, it is believed that the invention will be more clearly understood from the following detailed description of a preferred embodiment thereof, referring to the accompanying drawings, in which:

FIG. 1 is an end view, partially in section, of a turbine engine incorporating a starter nozzle according to the invention;

FIG. 2 is a fragmentary sectional end view showing the starter nozzle in relation to the engine casing and a nozzle diaphragm;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, looking in the direction of the arrows;

FIG. 4 is a fragmentary plan view of the starter nozzle;

FIG. 5 is a sectional view taken along line 55 in FIG. 3, looking in the direction of the arrows; and

FIG. 6 is a fragmentary pictorial view illustrating retaining keys locating the nozzle diaphragm relative to the engine casing.

Referring to the drawings, a turbine engine incorporating the improved starter nozzle includes a turbine wheel 10 rotatably mounted upon a shaft 11 and carrying a circumfcrentially spaced row of buckets 12 about the periphery thereof. An annular casing 13 is circumferentially spaced about the turbine, and is provided with radial flanges 14 and 15 at its longitudinal extremities for attachment to adjoining casing sections of a turbine engine by means of suitable fasteners (not shown) received in a plurality of peripheral openings 16 and 17. The casing is longitudinally split on a diametral plane at surfaces 18 to facilitate assembly of the turbine therein, and is formed with mating radial flanges 19 and 20 which are joined by suitable fasteners 21 to secure the assembly. The casing is also provided with a plurality of internal circumferentially extending flanges, one of which is shown at 22, for the purpose of supporting at least one turbine shroud ring 23 in the casing. The shroud ring is circumferentially spaced about the tips of the buckets 12 to prevent leakage of working fluid around them. A turbine nozzle diaphragm generally designated 24 is provided for directing working fluid to the turbine buckets, and includes a circumferentially-spaced row of partitions 25. The partitions extend radially between an inner composite mounting ring 26 and an outer composite mounting ring 27, which comprises an inner band 28 and an outer concentric band 29. The partitions extend radially through the inner and outer bands 28 and 29, except that along a portion of the outer ring cooperating with the starting nozzle, the partitions are interrupted in edges 30 at the inner band. The nozzle diaphragm is supported in a wellknown manner by the flange 22 and by an additional flange (not shown) spaced axially upstream in the casing. A working fluid flow path 31 is thus defined by the nozzle diaphragm and the shroud ring 23. The elements thus far described are generally of conventional construction, and further detailed description thereof is believed unnecessary.

For the purpose of introducing starting fluid into the turbine, a manifold 34 extends over an arcuate portion of the casing 13 and is brazed or otherwise secured thereto. Starting fluid, which may conveniently comprise air at a pressure of about 45 p.s.i., is introduced into an orifice 35 at a circumferential end of the manifold by any Wellknown means. Within the manifold, the casing is formed with a circumferentially-spaced series of ports 36 forming intermediate webs 37. The openings 36 are in the form of parallelograms, as best shown in FIG. 4. The provision of intermediate webs does not interfere with the air flow, and serves to maintain the rigidity of the casing in the region of the starting nozzle. The openings divide the flow of starting fluid, as shown by the arrows in FIG. 1, into a plurality of streams for direction to individual partitions of the nozzle diaphragm.

The starting nozzle includes a nozzle box 40 which comprises a circumferentially-spaced series of planar partition plates 41 inclined circumferentially and laterally of the casing. The plates are intersected by parallel leading and trailing edge surfaces 42 and 43, respectively, and by inner and outer edge surfaces 44 and 45, respectively. Edges 46 and 47, defined by the edge surface 44 with the planar surfaces, respectively, of each partition plate, are disposed parallel to lines tangent to the contoured surfaces of the nozzle partitions in the vicinity of the trailing edges thereof. The plates 41 pass through circumferentially extending openings 48 and 49 formed in the outer band 29 and the inner band 28, respectively, and are welded or brazed to the upper interrupted edges of corresponding nozzle partitions. A series of passageways 50 are thus formed between adjacent plates 41, communicating the manifold 34 through the ports 36 with the working fluid flow path 31 between adjacent partitions. The passageways 50 are enclosed by means of planar cover plates 51 and 52, which are brazed or welded to the upstream and downstream edges, respectively, of the plates 41, to enclose the passageways 5t) and to define their parallelogram cross-sectional form. The plate 52 is formed with an arcuate flange 53 abutting the outer band 29 and brazed thereto to aid in securely supporting the nozzle box upon the diaphragm.

The nozzle diaphragm 24 is circumferentially segmented at the split surface 18 for mounting in the casing halves. The segments are circumferentially slidable into the casing halves to a predetermined circumferential location in which their movement is stopped by a plurality of retaining keys 54, best shown by FIG. 6, which engage the circumferential end surfaces of the casing halves and the segments of the nozzle diaphragm at the split surfaces 18, The retaining keys are more fully described in a copending application of Louis E. Varadi, Theodore E. Bourque, and Walter Pesarek, entitled Retaining Means for Turbine Shrouds and Nozzle Diaphragms of Turbine Engines, now Patent 3,056,083, issued October 2, 1962. However, the specific means used for locating the nozzle diaphragm in a predetermined circumferential position are not critical to the present invention, and various wellknown means may be substituted for the retaining keys 54. Because the starting nozzle box is secured in a predetermined circumferential location upon the nozzle diaphragm, the alignment of the passageways 50 with the ports 36 of the casing automatically ensues upon the assembly of the elements of the engine.

While the planar surfaces of the partition plates of the nozzle box are not congruent with the curved surfaces of the trailing edges of the partitions, they provide a sufliciently close approximation to direct the starting fluid to the partitions in a satisfactory and effective manner.

The construction of the nozzle box of this invention provides advantages of simplicity and low manufacturing cost which offset its slight sacrifice of efficiency as compared with contoured starting nozzles. A plurality of the nozzle boxes may be incorporated in a single nozzle diaphragm if desired. For example, a pair of diametrically opposed nozzle boxes may be utilized. A selected one of these may be actuated, to afford increased accessibility in varying nacelle installations; or both may be actuated to obtain additional starting torque.

While we have shown and described a preferred embodiment of our improved starting nozzle by way of illustration, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. We therefore intend to cover all such changes and modifications in the appended claim.

What we claim and desire to secure by Letters Patent of the United States is:

In a gas turbine engine, the combination comprising; an annular segmented casing enclosing a working fluid flow path, said casing formed with a row of circumferentially spaced ports therein, webs forming an integral part of said casing separating adjacent ones of said ports, a turbine mounted for rotation in said working fluid flow path, an annular segmented nozzle diaphragm including a row of circumferentially-spaced partitions having contoured surfaces and arranged to direct a stream of working fluid into said turbine, said diaphragm further including a segmented band circumferentially spaced about said partitions and secured to radially outer edges thereof, a starter nozzle box comprising a plurality of planar partition plates spaced apart circumferentially about said nozzle diaphragm interiorly of said casing, each of said plates extending inwardly through said band to the outer edge of a corresponding partition and secured thereto, each of said plates having edges adjacent to the corresponding partition disposed parallel to a tangent to a trailing edge portion of curved surfaces of the correponding partition, an outer edge of each of said plates abutting said casing interiorly thereof, and retaining means engaging circumferential end surfaces of the segments of said casing and said diaphragm to locate said diaphragm and said nozzle box in predetermined circumferential position with respect to said casing, said predetermined position being such that each of said ports is located intermediate said outer edges of an adjacent pair of said plates for admitting starting fluid between said adjacent pair of said plates and the corresponding partitions to said turbine.

References Cited in the file of this patent UNITED STATES PATENTS 2,959,919 Chiera Nov. 15, 1960 2,971,333 Mendelsohn Feb. 14, 1961 2,989,848 Palement June 27, 1961 FOREIGN PATENTS 615,689 Great Britain Jan. 10, 1949 

